LWP::Protocol - Base class for LWP protocols
package LWP::Protocol::foo;
use parent qw(LWP::Protocol);
This class is used as the base class for all protocol implementations
supported by the LWP library.
When creating an instance of this class using
LWP::Protocol::create($url), and you get an initialized subclass
appropriate for that access method. In other words, the
create in the LWP::Protocol manpage function calls the constructor for one of its
subclasses.
All derived LWP::Protocol classes need to override the request()
method which is used to service a request. The overridden method can
make use of the collect() method to collect together chunks of data
as it is received.
The following methods and functions are provided:
my $prot = LWP::Protocol->new();
The LWP::Protocol constructor is inherited by subclasses. As this is a
virtual base class this method should not be called directly.
my $prot = LWP::Protocol::create($scheme)
Create an object of the class implementing the protocol to handle the
given scheme. This is a function, not a method. It is more an object
factory than a constructor. This is the function user agents should
use to access protocols.
my $class = LWP::Protocol::implementor($scheme, [$class])
Get and/or set implementor class for a scheme. Returns '' if the
specified scheme is not supported.
$response = $protocol->request($request, $proxy, undef);
$response = $protocol->request($request, $proxy, '/tmp/sss');
$response = $protocol->request($request, $proxy, \&callback, 1024);
Dispatches a request over the protocol, and returns a response
object. This method needs to be overridden in subclasses. Refer to
the LWP::UserAgent manpage for description of the arguments.
my $res = $prot->collect(undef, $response, $collector); # stored in $response
my $res = $prot->collect($filename, $response, $collector);
my $res = $prot->collect(sub { ... }, $response, $collector);
Collect the content of a request, and process it appropriately into a scalar,
file, or by calling a callback. If the first parameter is undefined, then the
content is stored within the $response. If it's a simple scalar, then it's
interpreted as a file name and the content is written to this file. If it's a
code reference, then content is passed to this routine.
The collector is a routine that will be called and which is
responsible for returning pieces (as ref to scalar) of the content to
process. The $collector signals EOF by returning a reference to an
empty string.
The return value is the the HTTP::Response manpage object reference.
Note: We will only use the callback or file argument if
$response->is_success(). This avoids sending content data for
redirects and authentication responses to the callback which would be
confusing.
$prot->collect_once($arg, $response, $content)
Can be called when the whole response content is available as content. This
will invoke collect in the LWP::Protocol manpage with a collector callback that
returns a reference to $content the first time and an empty string the
next.
Inspect the LWP/Protocol/file.pm and LWP/Protocol/http.pm files
for examples of usage.
Copyright 1995-2001 Gisle Aas.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
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